The present invention generally relates to heat pipe devices and more particularly pertains to the improvement of such devices. Specifically, the improvements encompass enhanced heat transfer efficiency as well as increased mechanical strength, conformability to a wide variety of geometric configurations, a reduction of specific weight and volume and manufacturability at relatively low cost.
Heat pipes provide a heat transfer function with a structure that is wholly devoid of moving parts. Such devices generally include a combination of relatively large conduits and small capillary-like structures that extend between two surfaces, one such surface being adjacent a heat source and the other being adjacent a heat sink. A quantity of coolant is contained within the device wherein the coolant is selected so as to evaporate upon contact with the hot surface and condense upon contact with the cold surface. The conduits enable the transport of vaporized coolant toward the heat sink where it reassumes its liquid state while the capillary structure facilitates the return of the liquid coolant to the heat source by capillary action. The coolant is thereby available for the continuous repetition of the cycle.
Various structural configurations have been found to be effective as heat pipe devices including a fabricated honeycomb structure that is capped by faceplates and lined with mesh material. The interior space of each honeycomb cell functions as a vapor conduit while the mesh performs the function of a capillary-like structure to wick liquid coolant from the cold to the hot faceplate. Efforts to enhance the heat transfer capacity of such devices have typically entailed the substitution of various composite materials for the aluminum normally used in the construction thereof. Additionally, because such devices are often intended for applications with strict space and weight limitations, it is most desirable to minimize both their weight and volume. It is especially preferable to have the ability to wholly integrate a heat pipe device within structural components that are necessarily associated with a particular application. For example, a heat pipe structure integrated within the walls, struts, and/or shelves of a satellite could fulfill the heat transport/rejection requirements without taking up space or adding weight to the spacecraft. The feasibility of a particular heat pipe design for such applications not only depends upon its specific heat transfer capacity, both in terms of weight and volume, but also its configurability to a wide range of geometries and orientations. These capabilities must be available without compromise to the structural strength while the device must nonetheless be economical to manufacture. The previously known devices have been unable to adequately fulfill all these requirements simultaneously especially as necessitated in microsatellite applications.